This invention relates to an apparatus and method to count closely spaced variations of light intensity; more specifically, it relates to a method and apparatus to count crimps in a moving tow of yarn. The method and apparatus can also be used whenever the number of striations in a target is required to be counted.
The amount of crimp or number of crimps per inch is an important parameter in the useful properties of natural or synthetic yarns used to manufacture apparel, carpet or other fabrics where bulkiness is required.
The most common method of counting the number of crimps per inch in yarn has been to cut away the sample, magnify it, and count the number of crimps by the human hand and eye. This slow and expensive method does not make possible in-line control of a crimping apparatus to control the number of crimps per inch during the crimping process. An instantaneous measurement, if only to indicate a quick measurement for operator control, has been a desirable need in the art. Either or both of these needs have been met with applicants' invention.
However, it is known in the prior art in Japanese Pat. No. 50-18,099 to Toray Industries to continuously measure the number of crimps with a light source arranged so that the angle of the ray projected reflects at a specific angle into a photoelectric tube and the number of crimps is measured by detecting the overall intensity (not the closely spaced variations) of the reflected ray. This disclosure is the only disclosure known to us of a method and apparatus to measure the number of crimps in tow. Other less pertinent patents are as follows:
U.S. Pat. No. 3,709,610 measures the thickness of a filament using a known wavelength light, such as a laser, and picking up the diffraction pattern of the refracted light passing through the single filament in a detector array and the spacings between the light and dark portions of the diffraction pattern is measured to provide an indication of the diameter of the filament.
U.S. Pat. No. 3,719,425 is also a method for measuring the dimension of an object by employing a Topler optical arrangement where light rays reflected from a parallel path are conducted to a photoelectric receiver which provides an electrical output signal responsive to the intensity of the deflected light rays. The intensity is a measure of the dimension of the object.
U.S. Pat. No. 3,669,552 is a method and apparatus for spreading and counting filaments in a yarn. A continuous light source is used and the filaments must traverse a slot over a photocell in order to be counted.
U.S. Pat. No. 3,777,557 takes a series of photographs using a stroboscopic light as a single strand is tested by applying force to stretch it.
In U.S. Pat. No. 3,936,917, automatic control of the discharge end of a stuffer box crimper is disclosed. The controller is connected to a jet pressure sensor which controls the exit gate at the crimper box to control the exit location of the end of the crimped wad of yarn.
U.S. Pat. No. 3,814,494 discloses uniformly scaning a flat surface of a paper sheet by reflecting it with a rotating mirror from a light beam.